Methyl hydrazine

CAS number: 60–34–4

NIOSH REL: 0.04 ppm (0.08 mg/m³) 2-hour CEILING; NIOSH considers methyl hydrazine to be a potential occupational carcinogen as defined by the OSHA carcinogen policy [29 CFR 1990].

Current OSHA PEL: 0.2 ppm (0.35 mg/m³) CEILING [skin]

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 0.2 ppm (0.38 mg/m³) CEILING [skin], A2

Description of substance: Fuming, colorless liquid with an ammonia-like odor.

LEL: . . . 2.5% (10% LEL, 2,500 ppm)

Original (SCP) IDLH: 50 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the report by Jacobson et al. [1955] of a mouse LC₅₀ of 56 ppm.

Short-term exposure guidelines: National Research Council [NRC 1985] Short-term Public Emergency Guidance Levels (SPEGLs):

1-hour SPEGL: 0.24 ppm

2-hour SPEGL: 0.12 ppm

4-hour SPEGL: 0.06 ppm

8-hour SPEGL: 0.03 ppm

16-hour SPEGL: 0.015 ppm

24-hour SPEGL: 0.01 ppm

ACUTE TOXICITY DATA:

Lethal concentration data:

Species	Reference	LC50 (ppm)	LCLo (ppm)	Time	Adjusted 0.5-hr LC (CF)	Derived value
Rat Rat Monkey Dog Monkey Mouse Rat Mouse Hamster	Fairchild 1967 Haun et al. 1969 Haun et al. 1969 Haun et al. 1970 Haun et al. 1970 Haun et al. 1970 Haun et al. 1970 Jacobson et al. 1955 Jacobson et al. 1955	34 74 162 195 145 272 427 56 143	----- ----- ----- ----- ----- ----- ----- ----- -----	4 hr 4 hr 1 hr 30 min 30 min 30 min 30 min 4 hr 4 hr	68 ppm (2.0) 148 ppm (2.0) 203 ppm (1.25) 195 ppm (1.0) 145 ppm (1.0) 272 ppm (1.0) 427 ppm (1.0) 112 ppm (2.0) 286 ppm (2.0)	6.8 ppm 15 ppm 20 ppm 20 ppm 15 ppm 27 ppm 43 ppm 11 ppm 29 ppm

Human data: None relevant for use in determining the revised IDLH.

Revised IDLH: 20 ppm Basis for revised IDLH: The revised IDLH for methyl hydrazine is 20 ppm based on acute inhalation toxicity data in animals [Haun et al. 1969, 1970]. [Note: NIOSH recommends as part of its carcinogen policy that the "most protective" respirators be worn for methyl hydrazine at concentrations above 0.04 ppm.]

REFERENCES:

1. Fairchild EJ II [1967]. Toxic Hazards Research Unit annual technical report: 1967. Wright-Patterson Air Force Base, OH: Aerospace Medical Research Laboratory, Report No. AMRL-TR-67-137, pp. 1-58.

2. Haun CC, MacEwen JD, Vermont EH, Egan GF [1969]. The acute inhalation toxicity of monomethyl hydrazine vapor. Wright-Patterson Air Force Base, OH: Aerospace Medical Research Laboratory Report No. AMRL-TR-68-169.

3. Haun CC, MacEwen JD, Vernot EH, Egan GF [1970]. Acute inhalation toxicity of monomethylhydrazine vapor. Am Ind Hyg Assoc J 31:667-677.

4. Jacobson KH, Clem JH, Wheelwright HJ, Rinehart WE, Mayes N [1955]. The acute toxicity of the vapors of some methylated hydrazine derivatives. AMA Arch Ind Health 12:609-616.

5. NRC [1985]. Emergency and continuous exposure guidance levels for selected airborne contaminants. Vol. 5. Washington, DC: National Academy Press, Committee on Toxicology, Board on Toxicology and Environmental Health Hazards, Commission on Life Sciences, National Research Council, pp. 23-35.